Overrunning clutches are integral to helicopter drive systems, automotive transmissions, and many other applications. In helicopter drive trains, overrunning clutches permit the main rotors to continue to rotate in the event of engine failure.
Conventional clutch configurations use friction and high contact stresses as means for transferring load through the clutch. The generated friction is affected by lubricant properties and temperatures. Such conventional clutches are susceptible to wear, operational problems with unreliable engagements, and even catastrophic failure. They are also heavy because of the thickness and surface area of the components required to carry the torque load with friction.